The invention relates to a method for determining a target steering torque for a steering means of a steering device in a vehicle.
The invention also relates to a steering device in a vehicle. The invention further relates to a computer program that can be executed on a control unit of a steering device in a vehicle, and to a memory medium on which the computer program is stored.
In modern steering devices, for example in an electric power steering (EPS) system or in what is referred to as a Steer-by-Wire (SbW) steering system, a target steering torque is determined, which is applied to a steering means, for example a steering wheel, in order to counteract or support the force applied by the driver. The target steering torque is frequently generated based on an actual toothed rack force acting on the wheels of the vehicle so as to provide the driver with the appropriate steering assistance. Additionally, further functions may be involved in generating the target steering torque so as to achieve a desired and pleasant steering feel for the driver. A toothed rack force determined by competent methods can provide the forces or force conditions actually present at the front axle of the vehicle, or at the toothed rack. If this force is used as a basis for generating what is referred to as a desired steering torque, the driver generally obtains good feedback on the behavior of the vehicle, or on the conditions of the roadway. In addition to the basic steering torque thus generated, additional functions can be added in a module-like manner so as to provide the desired steering torque.
The generation of a target steering torque based on the actual toothed rack force is dependent on several variables or pieces of information. The road friction value and the current driving condition are some of the factors affecting the toothed rack force. In principle, some of this information is helpful and desired by the driver. Other parts of the information, in contrast, are considered to be disturbing. Put simply, it can be stated that information about variables that influence the straight-ahead position of the vehicle may not be desired by the driver, wherein the particular circumstances may need to be looked in great detail. Moreover, it may be difficult to provide a behavior of the target steering torque which is desired by the driver in the center point range of the steering, while achieving a low-disturbance straight-ahead position of the vehicle.